Dehydrating rubber deposited from aqueous dispersions

ABSTRACT

299,713. Anode Rubber Co., Ltd., (Assignees of Darby, C. L.). Oct. 28, 1927, [Convention date]. Coagulating.-Electric endosmose is employed in the removal of water from layers or articles of rubber or like substance formed from an aqueous dispersion. In one method a metal plate coated with rubber is connected as anode while immersed in mercury or an electrolyte; exposed parts of the plate not coated with rubber are coated with wax or other insulating composition. In another method the coated plate, connected as anode, is placed between two metal plates connected as cathodes. In the apparatus shown, a wire or strip 32 is passed through an insulating seal 33 of soft vulcanized rubber in the base of a tubular tank 30 connected as cathode and is thereby coated with rubber or like substance from a dispersion in the tank. The coated wire then passes through a vessel 35, connected as a cathode, containing a conductive liquid for dehydration, and then to a final drying chamber 39. The wire is connected to the generators B, E by brushes 34. The depositing voltage may be 20-60 and the drying voltage 20-110. In a modification the coated wire is passed for dehydration between pairs of rollers connected as cathodes instead of through a conductive liquid. The invention may be applied to the dehydration of coated fabrics.

Feb. 28, 1933. E H DARBY 1,899,5Hfi

DEHYDRATING RUBBER DEPOSITED FROM AQUEOUS DISPERSIONS Filed Oct. 28, .1927

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grams. The plate was then made the positive ole and dipped into the cup of mercury whic was made the negative pole. A current at 70 volts was applied for 20 seconds at the end of which time the weight of the rubber deposit was reduced to 4.5 ams or a loss in weight of 35.6 percent base on weight of the dry rubber content, the original water content of the deposit being about 40 percent.

The construction of 2 is useful in drying flat sheets of rubber freshly formed from ,an aqueous dispersion thereof. The metal plate 20 with its covering of freshly deposited rubber 21 is placed between the metal plates 22. The plates 20 and '22 are connected respectively to the positive and negative poles of an electric current source as by leads 23 and 24. When the current is ap lied, the water is rapidly driven out from t e rubber de osit. I

n Fig. 3 is shown. an apparatus for contin uously coating continuous lengths of strip material, such as wire, with an insulating compound from an aqueous dispersion thereof and for continuously removing the water from the insulation. A long tubular tank or receptacle 30, preferably of electro-conductive material, is adated to contain an aqueous dispersion 31 0 any desired insulating compound and to be connected'with the negative pole of a current source B. A wire 32, or other strip material, is arranged to be drawn upwardly through the tubular tank,

the wire entering the tank through an insula-.

tor 33, preferably made of soft vulcanized rubber, which also serves to seal against leakage about the wire. Situated below the tank are brushes 34 which contact with the wire 32- and are connected to the positive pole of the above mentioned current source B'as well as to a second current source E.

Disposed in convenient juxtaposition to the depositing tank 30 is a dehydrating cham ber 35 containing an electro-conductlng liquid 36, which is connected to the negative pole of the current source E. Suitable uiding and supporting members for the insu ated wire 37 as it leaves the tank 30 and pames to, through and from the chamber 35am provided, such as rollers 38. In certain cases it may be desirable further to dry the insulation of the wire as it leaves the dehydrating,

chamber 35. For this purpose, a drying chamber 39 may be employed for removing residual moisture after the insulated wire has been treated in the chamber 35, although it is to be understood that such drying chamberv may be omitted or other processing mechanisms may be inserted either before or after the insulated wire has traversed the chamber 35, if necessary or desirable.

The construction shown in Fig. 4 is similar to that of Fig: exce t that the liquid containing dehy ting c am er 35 is replaced by the metal shives or grooved rollers 40, of which one, two or more sets may be employed, connected to the negative pole of the current source E, and between which rollers 40 the insulation is both compressed mechanically and acted upon electro-endosmotically to remove water from the deposit.

The operation of the constructions of Figs. 3 and 4 is obvious from the above description. Briefly, the wire 32 is'continuous y passed upwardly through the tubular tank 30 filled with an aqueous dispersion of an insulating compound. A current of the order of from 20 to volts, although a higher or lower voltage may beused, is passed between the tank 30 and the wire 32 through the aqueous dispersion" 31, and gradually builds up by electrodeposition on the wire 32 as it traverses the tank 30 a layer of the solid constituents of the dispersion. The coated wire 37 is then led to the dehydratin device.

In the apparatus 0 Fig. 3 the second current of the order from 20 to 110 volts, more or less, passes betweenthe wire 32 and the electro-conductive liquid 36 through the insulating coating, resulting'in a rapid driving out of the moisture from the insulation, the water removed mingling with the liquid 36. Since. the rate of removal of'the water increases with increase of thepotential of the current employed, relatively, high voltage currents acting for short periods are preferred. The effect of high voltage currents upon the deposit is. however, to increase the resistance'to flow of current through the de posit and the voltage of the current should not for this reason be made excessively high. The surface moisture and the'residual moisture may be removed by one or more drying chambers 39. i

In the apparatus of Fig. 4, the insulated strip or wire passes from the depositing bath of tank 30 to one or more sets of grooved rollers 40, the latter compacting and the high potential current from source E endosmotically driving out the water from the deposited insulation. The residual moisture may be removed by evaporation, as in drying chamber 39, or y other suitable means.

It will be understood that rinciples of the invention herein specifically described as applicable to the coating of wire or other electro-conductive material is also applicable to the coating of fibrous materials, either in woven or unwoven form, and other per-vious or porous materials. Thus, threads, cords and woven fabrics impregnated with suitable electrolytes may be coated with an aqueous rubber dispersion by spraying, dipping, spreading, or other suitable means, and then subjected to a dehydratingaction by the process herein described.

The term electrically-conductive materia1 is accordingly used in the present specification and claims in a generic sense to inelude metals or other solid conductors of electricity, and also to include ervious or porous bodies normally electrically-nonconductive, the interstices of which contain conductive substances in a suflicient degree to make such treated bodies efi'ectively electroconductive.

It will be clearfrom the above description that the present invention deals primarily with the removal of moisture from relatively thick deposits of rubber by an electro-osmotic action and that it has the advantage of speed and efliciency and of being accomplished without skin formation at the exterior surface of the deposit which would retard' escape by evaporation of residual moisture. v

While several embodiments of this invention have been hereinabove described, it is to be understood that numerous other moditications and variations may be made therein without departing from the princi les of this invention, and it is therefore not esired to limit the invention otherwise than necessitated by the prior art.

What is claimed is:

1. The process of covering continuous lengths of electrically-conductive material with a layer of normally electrically-nonconductive lastic material which comprises progressive y depositing said electricallynon-conductive material in the form of an aqueous dispersion onto the electrically-conductive material, and thereafter progressively driving oii from said body at least a part of its water content by electro-endosmosis.

2'. The process of covering continuous lengths of electrically-conductive material with a layer of a rubber composition which comprises'progressively passing said electrically-conductive material through an aqueous dispersion of a rubber composition, and dcpositing thereon b electrophoresis during such passa e a b y comprising solid constituents 0 said dispersion, thereafter continuing the progressive movement of the elec trically-con uctive material to bring its covering comprising said deposited body into and out of surface contact with a conductor of electricity and passing a relatively high potential electric current through said deposited body during said contact, the said conductor serving as a cathode.

3. In the herein described process of building an article comprising rubber from an aqueous dispersion of rubber composition in which a self-sustaining body of said rub er composition is first formed from, and then removed from, the a ueous dispersion so that it comprises both dispersed and disgersing constituents, the step which includes riving off from said self-s'ustainingzbody at least a part of the dispersing constituents by electro-endosmosis;

4, In the herein described process of'building an article comprising rubber and an electrically conductive backing material, in which a selfsustaining bod of rubber composition is formed on the acking material from an aqueous dis ersion of such rubber composition, said sel -sustaining body comprising dispersing constituents, the step which comprises passing an electric current through said self-sustaining body by direct application of a cathodic body to the surface of said self-sustaining body, said electrically conductive material serving as an anode.

5. The process of covering an electro-conductive body with a layer of a rubber composition which comprises immersin the said material in an aqueous dispersion o a rubber composition, passing an electric current through the dispersion to the said body as an anode to deposit the solid content of the dispersion thereon, removing the body from the dispersion, placing its covering in contact with a conductor of electricity, and passing a second relatively high potential electric current through the deposit to the said body inthe same direction.

In witness whereof I have hereunto set my hand this 15th day of October, 1927 CORNELIA L. DARBY, Emecutm'w of the Estate of Edward H. Darby,

Deceased. 

